Silicon-containing particles represented by silicone rubber particles are used as a raw material for cosmetic products, an additive to organic resins, etc. A known method of manufacturing the silicon-containing particles consists of curing a curable silicone composition in a state emulsified in an aqueous solution of a surface-active agent (hereinafter referred to as surfactant). For example, known in the art is a method of forming silicone rubber particles by emulsifying and curing a curable silicone composition that contains a non-cross-linkable silicone oil, thus obtaining silicone-rubber particles in oil droplets of the emulsion (see Japanese Unexamined Patent Application Publication (hereinafter referred to as “Kokai”) 2000-281903).
However, silicon-containing particles manufactured by the method described above contain a large amount of surfactants. Therefore, such particles lose heat-resistant, electrical, and other properties that could be introduced by the silicon-containing particles per se. Furthermore, in the above method, control of the particle diameter by selecting types and concentrations of surfactants, or the emulsification capacity of the emulsifier, is applicable exclusively to particles of relatively large diameters, but control becomes more difficult the smaller is the diameter of the particles.
On the other hand, known in the art is a method of manufacturing a ceramic material that contains Si, O, and C by thermally decomposing a composition that includes a silicon-containing precursor (see Kokai H10-074506 and Kokai H10-275617) or by impregnating graphite with one or more kinds of organic silicon compounds selected from cross-linkable silanes and siloxanes, forming a cross-linked product from the above organic silicon-containing compound in the graphite, and heating and reacting the graphite in a non-oxidative gas at 300 to 1200° C., thus obtaining a C/Si/O-based composite material (see Kokai 2003-171180).
However, when the ceramic materials obtained by the above methods are subjected to grinding for obtaining microparticles, the resulting fine particles are obtained in irregular shapes which do not provide desired flowability and filling properties that are inherent in fine spherical particles.
It is an object of the present invention to provide a method for manufacturing silicon-containing particles of an extremely small diameter in a simple process without the use of surfactants, or the like. It is another object to provide silicon-containing particles that can be produced with a controlled diameter, possess excellent dispersibility in oil, and which provide a high degree of ceramification upon baking. The invention also provides an oil composition with uniformly dispersed silicon-containing particles.
It is a further object of the invention to provide a method for manufacturing a ceramic material composed of particles of an extremely small and controllable diameter in a simple process. It is a still further object to provide a ceramic material that possesses the above-mentioned properties.